Researchers at the University of Washington (UW) have reported for the first time that mammals can be stimulated to regrow inner nerve cells in their damaged retinas. Located in the back of the eye, the retina's role in vision is to convert light into nerve impulses to the brain.
The findings on retina self-repair in mammals will be published this week in the Early Edition of the Proceedings of the National Academy of Sciences. Other scientists have shown before that certain retina nerve cells from mice can proliferate in a laboratory dish. Today's report gives evidence that retina cells can be encouraged to regenerate in living mice.
The UW researchers in the laboratory of Dr. Tom Reh, professor of biological structure, studied a particular retinal cell called the Mller glia.
"This type of cell exists in all the retinas of all vertebrates," Reh said, "so the cellular source for regeneration is present in the human retina." He added that further studies of the potential of these cells to regenerate and of methods to re-generate them may lead to new treatments for vision loss from retina-damaging diseases, like macular degeneration.
The researchers pointed out the remarkable ability of cold-blooded vertebrates like fish to regenerate their retinas after damage. Birds, which are warm-blooded, have some limited ability to regenerate retinal nerve cells after exposure to nerve toxins. Fish can generate all types of retinal nerve cells, the researcher said, but chicks produce only a few types of retinal nerve cell replacements, and few, if any, receptors for detecting light.
Mller glia cells generally stop dividing after a baby's eyes pass a certain developmental stage. In both fish and birds, the researchers explained, damage to retinal cells prompts the specialized Mller glia cells to start dividing again and to increase their options by becoming a more general type of cell called a progenitor cell. These prog
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